1. Field of the Invention
This invention relates to a method for the production of a photoelectrochemical cell for converting light energy into electric energy and to a photoelectrochemical cell produced by the method.
2. Prior Art Statement
The wet type photoelectrochemical cell using a semiconductor electrode has been attracting attention as a cell of the type for converting light energy into electric energy.
First, the construction of the conventional wet type photoelectrochemical cell (hereinafter referred to briefly as "photo cell") will be described.
This wet type photo cell comprises a cell housing, an aqueous electrolyte solution placed in the cell housing, and a semiconductor electrode and a counter electrode of platinum opposed to each other and immersed in the aqueous electrolyte solution and produces electric energy by exposing the surface of a semiconductor to the light introduced through a transparent window formed in the cell housing.
Since the semiconductor electrode is immersed in the aqueous electrolyte solution, this wet type photo cell has the disadvantage that the semiconductor is deteriorated by oxidation and dissolved in the aqueous electrolyte solution, frequently to the extent of shortening the service life of the electrode rapidly degrading the quality of the electrode. As a solution of this problem, there has been proposed a photo cell using a solid electrolyte in place of the aqueous electrolyte solution [as proposed by T. Skotheim, I. Lundstrom, J. Electrochem. Soc., 129, 894 (1982), for example]. Unfortunately, this photo cell is deficient in stability. A photo cell using a semiconductor electrode coated with a thin film of platinum and a thin film of polypyrrole produced by the photoelectrolytic polymerization method [reported in the same literature as described above] has been under experiment. This photo cell is still deficient in stability. The surface of the semiconductor is susceptible to deterioration because the thin polymer film is formed by the photoelectrolytic polymerization method. As a result, the photo cell is inferior in quality and incapable of providing stable use for a long time. Moreover the production of this photo cell requires an immense amount of labor.
Under the circumstances, there has been expressed an earnest desire to develop a photo cell which provides stable use for a long time without a lowering its performance and which is easy to manufacture.